Field of the Invention
Embodiments of the invention relate generally to methods for processing a substrate during semiconductor manufacturing. Specifically, embodiments of the invention relate to methods of treating a nucleation layer prior to a CVD deposition process.
Description of the Related Art
Reliably producing nanometer-sized features is one of the key technologies for the next generation of semiconductor devices. The shrinking dimensions of circuits and devices have placed additional demands on processing capabilities. The multilevel interconnects that lie at the heart of integrated circuit technology require precise processing of high aspect ratio features, such as vias and other interconnects. Reliable formation of these interconnects is very important to future success and to the continued effort to increase circuit density and quality of individual substrates.
Metallization of features formed on substrates includes CVD deposition of metals such as tungsten. Tungsten can be used for metal fill of source contacts, drain contacts, metal gate fill and gate contacts as well as applications in DRAM and flash memory. With technology node shrinkage, tungsten films are required to have low resistivity and low roughness for device characteristics and for integration with subsequent process steps. Low resistivity in tungsten has been previously achieved by increasing the grain size. However, increased grain size results in increased film roughness. Typical roughness of low resistivity tungsten film is approximately 15% of film thickness.
Therefore, there is much effort in the art to improve the tungsten film morphology while maintaining the low film resistivity.